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<head>
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    <title>Document</title>
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        div {
            width: 300px;
            height: 249px;
            background-color: pink;
        }
    </style>
</head>

<body>
    <div id="box"></div>
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        var box = document.querySelector('#box')
        box.onmousemove = function(e) {

            var x = e.pageX - this.offsetLeft
            var y = e.pageY - this.offsetTop
            box.innerHTML = `x坐标是${x},y坐标是${y}`

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</body>

</html>